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Abstract:

Methods and devices for determining the operating mode of an implantable
medical device are disclosed. A first device transmits a keep-alive
signal to an implantable medical device. If the implantable medical
device receives the keep-alive signal within a first time interval, the
implantable medical device operates in a normal operating mode. If the
implantable medical device does not receive the keep-alive signal with
the first time interval, at least a portion of the implantable medical
device is deactivated.

Claims:

1. A method comprising: receiving at a hearing prosthesis a first
transmission of a signal; starting a timer for an interval of time in
which to receive a second transmission of the signal; determining whether
the hearing prosthesis received the second transmission of the signal
prior to an expiration of the timer; in response to determining that the
hearing prosthesis received the second transmission of the signal prior
to the expiration of the timer, delivering a first stimulus to a body
part of a recipient; and in response to determining that the hearing
prosthesis failed to receive the second transmission of the signal prior
to the expiration of the timer, delivering a second stimulus to the body
part, wherein a current of the first stimulus is greater than a current
of the second stimulus; and the first stimulus and the second stimulus
cause the recipient to perceive at least a portion of a sound.

2. The method of claim 1, wherein receiving the first transmission of the
signal activates the hearing prosthesis.

3. The method of claim 1, wherein the signal includes a signal
identifier.

4. The method of claim 3, further comprising: determining that the signal
identifier contained in the first transmission of the signal matches a
link identifier unique to the hearing prosthesis; and activating the
hearing prosthesis upon determining that the signal identifier matches
the link identifier.

5. The method of claim 3, wherein determining that the hearing prosthesis
failed to receive the second transmission of the signal prior to the
expiration of the timer includes determining that the signal identifier
contained in the second transmission of the signal and a link identifier
unique to the hearing prosthesis are different.

6. The method of claim 1, further comprising: determining a number of
consecutive intervals in which the hearing prosthesis failed to receive a
second transmission of the signal; determining whether the number exceeds
a threshold value; and in response to determining that the number exceeds
the threshold value, deactivating a stimulation component of the hearing
prosthesis that delivers the first stimulus and the second stimulus to
the body part.

7. (canceled)

8. A method comprising: determining a number of missed signals in a
sample interval, wherein the number of missed signals includes a first
number of time intervals in which a hearing prosthesis configured to
stimulate a body part of a recipient to cause a recipient to perceive a
portion of a sound failed to receive a signal, and wherein the sample
interval comprises a second number of time intervals in which the signal
could have been received; making a first determination that includes
determining whether the number of missed signals is less than a first
value that represents a first allowable number of time intervals in which
the hearing prosthesis failed to receive the signal; and selecting an
operating mode of the hearing prosthesis implantable medical device based
on the first determination, wherein a maximum amplitude of a stimulus
delivered by the hearing prosthesis to the body part depends on the
operating mode.

9. The method of claim 8, wherein the operating mode is at least one of:
a normal operating mode, wherein the maximum amplitude of the stimulus is
a first maximum amplitude in the normal operating mode; a safe operating
mode, wherein the maximum amplitude of the stimulus is a second maximum
amplitude in the safe operating mode, wherein the second maximum
amplitude is less than the first maximum amplitude; and a deactivated
mode, wherein the maximum amplitude of the stimulus is zero in the
deactivated mode.

10. The method of claim 9, further comprising sending an output signal to
a component of the hearing prosthesis, wherein the output signal
indicates the operating mode of the hearing prosthesis.

11. The method of claim 9, wherein the operating mode of the hearing
prosthesis is the normal operating mode when the first determination
indicates that the number of missed signals is less than the first value.

12. The method of claim 9, wherein the operating mode of the hearing
prosthesis is the deactivated mode when the first determination indicates
the number of missed signals is greater than or equal to the first value.

13. The method of claim 9, wherein the operating mode of the hearing
prosthesis is the safe operating mode when the first determination
indicates that the number of missed signals is greater than or equal to
the first value.

14. The method of claim 9, further comprising: making a second
determination that includes determining whether the number of missed
signals is less than a second value that represents a second allowable
number of time intervals in which the hearing prosthesis failed to
receive the signal, wherein the second value is less than the first
value.

15. The method of claim 14, wherein the operating mode of the hearing
prosthesis is the normal operating mode when the second determination
indicates that the number of missed signals is less than the second
value.

16. The method of claim 14, wherein the operating mode of the hearing
prosthesis is the safe operating mode when the first determination
indicates that the number of missed signals is less than the first value
and the second determination indicates that the number of missed signals
is greater than or equal to the second value.

17. The method of claim 14, wherein the operating mode of the hearing
prosthesis is the deactivated mode when the first determination indicates
that the number of missed signals is greater than or equal to the first
value.

18. A system comprising: a remote device configurable to transmit a
signal; and a hearing prosthesis configured to receive the signal within
in a time interval, wherein in response to the hearing prosthesis failing
to receive the signal within the time interval, a component of the
hearing prosthesis reduces amplitudes of stimuli delivered to a recipient
that cause the recipient to perceive at least a portion of a sound.

19. The system of claim 18, wherein the remote device includes an input
component, and wherein the remote device is further configurable to stop
transmitting the signal upon activation of the input component.

20. The system of claim 18, wherein the hearing prosthesis is deactivated
upon the hearing prosthesis failing to receive the signal more than a
threshold number of times in a monitoring interval, wherein the
monitoring interval is longer than the time interval.

21. The system of claim 18, wherein the transmission range of the remote
device ranges from about 1 meter to about 10 meters.

22. The system of claim 18, wherein the remote device is further
configurable to include at least one identifiers in the signal, and
wherein a link identifier is stored in a data storage of the hearing
prosthesis.

23. The system of claim 22, wherein the hearing prosthesis is further
configurable to determine whether at least one of the at least one
identifiers in the signal matches the link identifier, wherein the
hearing prosthesis fails to receive the signal upon determining that none
of the at least one identifiers in the signal match the link identifier.

24. The system of claim 23, wherein the link identifier is unique to the
remote device.

25. The system of claim 23, wherein the identifier is unique to the
hearing prosthesis.

26. A device comprising: a sensor configured to receive a sound from an
environment; a sound processor configured to receive a sensor output from
the sensor and generate a processed signal based on the sensor output; a
stimulating component configured to generate a stimulus that stimulates a
body part associated with auditory perception in a human body; an output
component configured to send an output signal to the stimulating
component, wherein the output signal includes information used to
generate the stimulus; a receiver configured to receive a first signal
from a remote device; and a processor configured to: determine whether
the receiver received the first signal within a first time interval; send
a first control signal to the output component in response to determining
that the receiver received the signal within the first time interval,
wherein the first control signal causes the output component to include
the processed signal in the output signal; and send a second control
signal to the output component in response to determining that the
receiver failed to receive the signal within the first time interval,
wherein the second control signal causes the output component to include
a portion of the processed signal in the output signal.

27. The device of claim 26 further comprising an antenna, wherein the
receiver is configured to receive the first signal via the antenna, and
wherein the antenna and the receiver are configured to receive the signal
in an industrial, scientific, and medical frequency band.

28. (canceled)

29. The device of claim 26, wherein including the portion of the
processed signal in the output signal causes the stimulation component to
generate a stimulus having a lower current than a stimulus generated
using the processed signal.

30. The device of claim 26, wherein the processor is further configured
to: determine whether the receiver received the first signal within a
second time interval, wherein the second time interval is longer than the
first time interval; and send a third control signal to the output
component in response to determining that the receiver failed to receive
the first signal within the second time interval, wherein the third
control signal causes the output component to stop sending the output
signal to the stimulating component.

Description:

BACKGROUND

[0001] Individuals who suffer from certain medical conditions may benefit
from the use of an implantable medical device. Depending on the type and
the severity of the medical condition, an individual can employ a
partially implantable medical device or a totally implantable medical
device. Partially implantable medical devices typically include an
external component that performs at least some processing functions and
an implanted component that at least delivers a stimulus to a body part
of a user, such as an organ. In the case of a totally implantable medical
device, the entire device is implanted in the body of a user.
Additionally, the implantable medical device is often configured to
communicate with a remote device that allows an individual to adjust a
component or a function of the implantable medical device.

SUMMARY

[0002] A method for determining an operating mode of an implantable
medical device is disclosed. In one example, the method includes
receiving a first transmission of a signal at the medical device. The
method also includes starting a timer for a time interval in which the
implantable medical device receives a second transmission of the signal.
Upon determining that the implantable medical device did not receive the
second transmission prior to the expiration of the timer, the method
includes deactivating at least a portion of the implantable medical
device.

[0003] A method for determining a number of missed signals in a sample
interval is also disclosed. The number of missed signals includes a first
number of time intervals in which the implantable medical device did not
receive a signal. The sample interval includes a second number of time
intervals in which the implantable medical device could have received the
signal. The method also includes making a first determination in which
the processor determines whether the number of missed signals is less
than the first value. The first value represents a first allowable number
of time intervals in which the implantable medical device did not receive
the signal. Additionally, the method includes selecting an operating mode
of the implantable medical device based on the first determination.

[0004] A system is also disclosed. The system includes a remote device
configurable to transmit a signal. The system also includes an
implantable medical device configured to receive the signal within a time
interval. If the implantable medical device fails to receive the signal
within the time interval, at least a portion of the implantable medical
device is deactivated.

[0005] Additionally, an implantable medical device is disclosed. The
implantable medical device includes a stimulating, an output component, a
receiver, and processor. The processor makes a first determination of
whether the receiver received the first signal in a first time interval.
Based on the first decision, the processor sends a second signal to the
output component that includes information indicating whether the output
component sends an output signal to the stimulating component.

[0006] These as well as other aspects and advantages will become apparent
to those of ordinary skill in the art by reading the following detailed
description, with reference where appropriate to the accompanying
drawings. Further, it is understood that this summary is merely an
example and is not intended to limit the scope of the invention as
claimed.

BRIEF DESCRIPTION OF THE FIGURES

[0007] Presently preferred embodiments are described below in conjunction
with the appended drawing figures, wherein like reference numerals refer
to like elements in the various figures, and wherein:

[0008]FIG. 1 is a block diagram of a communication system, according to
an example.

[0009]FIG. 2 is a block diagram of an implantable medical device depicted
in FIG. 1, according to an example.

[0010]FIG. 3 is a block diagram of a processing component that may be
part of the implantable medical device depicted in FIG. 2, according to
an example.

[0011]FIG. 4 is a block diagram of a remote device depicted in FIG. 1,
according to an example.

[0012]FIG. 5 is a flow diagram of a method for determining if a
keep-alive signal is received at an implantable medical device, according
to an example.

[0013]FIG. 6 is a flow diagram of a method for determining an operating
mode of an implantable medical device, according to an example.

DETAILED DESCRIPTION

[0014] The following detailed description describes various features,
functions, and attributes of the disclosed systems, methods, and devices
with reference to the accompanying figures. In the figures, similar
symbols typically identify similar components, unless context dictates
otherwise. The illustrative embodiments described herein are not meant to
be limiting. Certain aspects of the disclosed systems, methods, and
devices can be arranged and combined in a wide variety of different
configurations, all of which are contemplated herein.

[0015]FIG. 1 is a block diagram of a communication system 100. The
communication system 100 includes an implantable medical device 102 and a
remote device 104. The implantable medical device 102 receives a
keep-alive signal 106 from the remote device 104.

[0016] The implantable medical device 102 is configured to stimulate an
organ or a body part of a user. The implantable medical device may be
totally implantable or partially implantable depending on a user's
medical condition. In one example, the implantable medical device 102 is
totally implantable, and the implantable medical device 102 is implanted
in the user's body. In another example, the implantable medical device
102 is partially implantable, in which case a portion of the implantable
medical device 102 is externally attached to the user's body.

[0017] If the implantable medical device 102 does not receive the
keep-alive signal 106 within the specified time period, then at least a
portion of the implantable medical device 102 is deactivated. Thus, in
the event of an emergency or a malfunction, the user can deactivate at
least a portion of the implantable medical device 102 by turning the
remote device 104 off, which prevents the remote device 104 from
transmitting, and the implantable medical device 102 from receiving, the
keep-alive signal 106. Alternatively, the user or any other person can
move the remote device 104 away from the implantable medical device 102
such that the implantable medical device 102 is outside the transmission
range of the remote device 104.

[0018] The implantable medical device 102 is associated with the remote
device 104 such that the implantable medical device 102 only recognizes
keep-alive signals sent from the remote device 104. Associating the
implantable medical device 102 with the remote device 104 prevents the
implantable medical device 102 from receiving keep-alive signals
transmitted from other remote devices in the vicinity of the implantable
medical device 102.

[0019] The keep-alive signal 106 contains a signal identifier. The signal
identifier matches a link identifier stored in the implantable medical
device 102 in order for the implantable medical device 102 to properly
receive the keep-alive signal 106. In one example, the signal identifier
is unique to the remote device 104. In another example, the signal
identifier is unique to the implantable medical device. In yet another
example, the keep-alive signal 106 may include multiple signal
identifiers associated with multiple implantable medical devices. In this
example, at least one of the signal identifiers in the keep-alive signal
106 matches the link identifier stored in the implantable medical device
102 for the implantable medical device 102 to properly receive the
keep-alive signal 106.

[0020]FIG. 2 is a block diagram of an implantable medical device 200. The
implantable medical device 200 is one example of the implantable medical
device 102 of the communication system 100. The implantable medical
device 200 includes a processing component 202 and a stimulating
component 204.

[0021] In one example, the implantable medical device 200 is a totally
implantable medical device, such as a totally implantable cochlear
implant or an implantable cardioverter-defibrillator. In this example,
the processing component 202 and the stimulation component 204 are
implanted in a user's body. In another example, the implantable medical
device 200 is partially implantable, such as a conventional cochlear
implant, a bone-conduction device, an auditory-brain-stem implant, a
direct acoustic stimulation device, a hearing aid, and the like. When the
implantable medical device 200 is partially implantable, at least a
portion of the processing component 202 is externally attached to the
user's body.

[0022] The processing component 202 includes components for receiving a
stimulus. The processing component also includes components for
processing the stimulus and sending an output signal to the stimulating
component 204 via component link 206. The output signal includes
information indicating how the stimulating component 204 stimulates an
organ or body part of a user.

[0023]FIG. 3 is a block diagram of a processing component 300. The
processing component 300 includes a power supply 302, a sensor 304, a
sensor processor 306, an antenna 308, a receiver 310, a data storage 312,
a control processor 314, and an output interface component 316. The
processing component 300 also includes additional bus work (not shown)
and/or other electrical connections (not shown) connecting the components
of the processing component 300. The processing component 300 is one
example of the processing component 202 of the implantable medical device
200 depicted in FIG. 2.

[0024] The power supply 302 supplies power to various components of the
processing component 300 and can be any suitable power supply, such as a
non-rechargeable or rechargeable battery. In one example, the power
supply 302 is a battery that can be charged wirelessly, such as through
inductive charging. Such a wirelessly rechargeable battery reduces the
need for access to the processing component to replace the battery,
allowing for implantation of the processing component 300. In another
example, the power supply 302 is not a replaceable or rechargeable
battery and is configured to provide power to the components of the
processing component 300 for the operational lifespan of the implantable
medical device.

[0025] The sensor 304 receives a stimulus 318 and sends an input signal to
the sensor processor 306 that includes information about the stimulus. In
one example, the implantable medical device is a totally implantable
cochlear implant. In this example, the sensor 304 is an omnidirectional
microphone and the stimulus 318 is a sound. In another example, that
implantable medical device may be a bone-conduction device, an
auditory-brain-stem implant, a direct acoustic stimulation device, or the
like. In this example, the sensor 304 is an omnidirectional microphone, a
directional microphone, an electro-mechanical transducer, or any other
audio transducer suitable for use in the type of hearing prosthesis
employed. Furthermore, the sensor 304 includes one or more additional
sensors.

[0026] The sensor processor 306 receives an input signal from the sensor
304. In one example, the sensor processor 306 is a digital signal
processor and includes an analog-to-digital converter suitable for
converting the input signal, which is an analog signal, into a digital
input signal. In another example, the sensor processor 306 is any
processor suitable for processing the input signal. The sensor processor
306 converts the input signal into a processed signal and sends the
processed signal to the output interface component 316.

[0027] The antenna 308 receives a keep-alive signal 320 from a remote
device, such as the remote device 104 of the communication system 100. In
one example, the antenna 308 is configured to receive the keep-alive
signal 320 in the radio frequency ("RF") spectrum, preferably in an
industrial, scientific, and medical ("ISM") frequency band, such as a
band from about 2.4 GHz to about 2.5 GHZ. In another example, the antenna
308 is configured to receive the keep-alive signal 320 in a different ISM
band, such as a band from about 6.765 MHz to about 6.795 MHz, a band from
about 13.553 MHz to about 13.567 MHz, a band from about 26.957 MHz to
about 27.283 MHz, a band from about 40.660 MHz to about 40.700 MHz, a
band from about 433.050 MHz to about 434.790 MHz, a band from about
863.000 MHz to about 870.000 MHz, a band from about 902.000 MHz to about
928.000 MHz, a band from about 5.725 GHz to about 5.875 GHz, a band from
about 24.000 GHz to about 24.250 GHz, a band from about 61.000 GHz to
about 61.500 GHz, a band from about 122.000 GHz to about 123.000 GHz, or
a band from about 244.000 GHz to about 246.000 GHz. In still another
example, the antenna 308 is configured to receive the keep-alive signal
320 at a frequency outside of the RF spectrum. Furthermore, in yet
another example, the processing component 300 is configured to receive
the keep-alive signal as an infrared signal, an ultrasonic signal, a
magnetic signal, or any other similarly functioning signal. In this
example, the processing component 300 includes a device capable of
receiving the keep-alive signal 320 and may not include the antenna 308.

[0028] The receiver 310 receives the keep-alive signal 320 via the antenna
308. Additionally, the receiver 310 converts the keep-alive signal 320
into a converted keep-alive signal and sends the converted keep-alive
signal to the control processor 314. In one example, the receiver 310 is
configured to receive the keep-alive signal 320 in the RF spectrum,
preferably a signal in an ISM frequency band, such as a band from about
2.4 GHz to about 2.5 GHz, though the receiver 320 may receive the
keep-alive signal in a different ISM frequency band. In another example,
the receiver 310 is configured to receive the keep-alive signal outside
of the RF spectrum. Furthermore, in yet another example, the receiver 310
is configured to receive the keep-alive signal 320 as an infrared signal,
an ultrasonic signal, a magnetic signal, or a signal in any other medium
suitable for use in the communicating system 100.

[0029] The data storage 312 can be any type of non-transitory, tangible,
computer readable media known or later developed configurable to store
program code for execution by the processing component 300 and/or other
data associated with the processing component 300. In one example, the
data storage 312 stores a link identifier used by the control processor
314 for determining whether processing component 300 received the
keep-alive signal. The data storage 312 also stores the current operating
mode of the implantable medical device. In another example, the data
storage 312 also stores information indicating a current setting of a
parameter of the implantable medical device. For instance, when the
implantable medical device is a hearing prosthesis, the data storage 312
stores information indicating a current volume setting for the
implantable medical device.

[0030] The control processor 314 receives the converted keep-alive signal
from the receiver 310 and determines the operating mode of the
implantable medical device. In one example, the control processor 314 is
configured to determine the operating mode of the implantable medical
device upon receiving the converted keep-alive signal. In another
example, the control processor 314 executes instructions for determining
an operating mode of the implantable medical device 200. The data storage
312 stores the instructions for determining the operating mode of the
implantable medical device 200, which may include instructions for
implementing methods and processes disclosed herein, and the processor
314 accesses the instructions upon receiving the converted keep-alive
signal. In determining the operating mode of the implantable medical
device, the control processor 314 determines whether a signal identifier
in the converted keep-alive signal matches the link identifier.

[0031] In one example, the implantable medical device operates in a normal
operating mode, a safe operating mode, or a deactivated mode, though the
implantable medical device may operate in more or fewer operating modes
depending on the application. After determining the operating mode of the
implantable medical device, the control processor 314 sends a control
signal indicating the operating mode to the output interface component
316.

[0032] The output interface component 316 receives the control signal from
the control processor 314 and the processed signal from the sensor
processor 306. Additionally, the output interface component 316 sends an
output signal 322 to a stimulation component of an implantable medical
device, such as the stimulation component 204 of the implantable medical
device 200 depicted in FIG. 2.

[0033] In one example, the control signal indicates that the operating
mode of the implantable medical device is the normal operating mode. In
this example, the output signal 322 includes the processed signal, though
the output signal may include a parameter of an artificial stimulus based
on the processed signal. In another example, the control signal indicates
that the operating mode is the safe operating mode. In this example, the
output signal 322 includes a portion of the processed signal or a
parameter of the artificial stimulus based on a portion of the processed
signal. In yet another example, the control signal indicates that the
operating mode of the implantable medical device is the deactivated mode.
In this example, the output interface component 316 does not send the
output signal 322 to the stimulation component of the implantable medical
device.

[0034] Returning to FIG. 2, the stimulating component 204 receives an
output signal, such as the output signal 322 described in FIG. 3, from
the processing component 202 via a component link 206. The stimulating
component 204 also delivers an artificial stimulus 208 to an organ or a
body part of a user of the implantable medical device 200. In one
example, the implantable medical device 200 operates in the normal
operating mode. The output signal includes a processed signal, such as
the processed signal described in FIG. 3, and the stimulation component
204 utilizes the processed signal to deliver the artificial stimulus 208.

[0035] For example, consider a user with hearing loss. To alleviate this
condition, the user utilizes the implantable medical device 200, which is
a hearing prosthesis, such as a totally implantable cochlear implant. The
processing component 202 receives a sound from an environment, processes
the sound into the processed signal, and includes the processed signal in
the output signal sent to the stimulating component 204 via the component
link 206. The stimulating component 204 receives the output signal and
converts the output signal into the artificial stimulus 208, which in
this example is an electrical signal representing the sound. The
stimulating component 204 delivers the artificial stimulus 208 to a
region of the user's cochlea, thereby stimulating an auditory nerve and
allowing the user to perceive the sound.

[0036] In another example, the implantable medical device 200 operates in
a safe operating mode. In this example, the output signal includes a
portion of the processed signal. For instance, when the implantable
medical device 200 is a totally implantable cochlear implant, the output
signal includes a portion of an amplitude of the processed signal. The
stimulating component 204 receives the output signal and delivers the
artificial stimulus 208 to the user's cochlea at a reduced current as
compared to an artificial stimulus generated in the normal operating
mode. This has the effect of reducing the amplitude (e.g., volume) of the
sound perceived by the user.

[0037] In another example, the implantable medical device 200 is a hearing
prosthesis. When the implantable medical device 200 operates in the safe
mode, the output signal includes a certain frequency range of the
processed signal. For instance, the output signal includes information
from the processed signal inside a frequency range of about 60 Hz to
about 7 kHz. The resulting artificial stimulus 208 allows the user to
perceive a human voice, for example, but not a sound outside of the
typical human voice range. In yet another example, a different frequency
range is filtered from the processed signal based on the type of hearing
loss experienced by the user.

[0038] In still another example, the implantable medical 200 device
operates in the deactivated operating mode. In this example, the
processing component 202 does not send the output signal to the
stimulating component 204. Thus, the stimulating component 204 does not
deliver the artificial stimulus 208 to the organ or the body part of the
user.

[0039] Returning to FIG. 1, the remote device 104 may be worn on the
user's body by using, for example, a clip or a strap, though the user
does not need to wear the remote device 104 in order for the remote
device 104 to function properly. The remote device 104 is a stand-alone
electronic device that transmits the keep-alive signal. The remote device
may also be configured to send an additional signal to and receive a
signal from the implantable medical device 102. For example, the remote
device 104 may also allow a user or a medical professional to receive a
list of parameters from the implantable medical device 102 and send an
adjustment of a parameter to the implantable medical device 102. For
instance, if the implantable medical device 102 is a totally implantable
cochlear implant, the user or the medical professional can adjust the
sensitivity of an audio transducer.

[0040] The remote device 104 is configured to transmit the keep-alive
signal 106 in the RF spectrum, preferably in an industrial, scientific,
and medical ("ISM") frequency band, such as a band from about 2.4 GHz to
2.5 GHz. In another example, the remote device 104 transmits the
keep-alive signal 106 outside of the RF spectrum, such as a low-frequency
spectrum (e.g. <300 kHz). In yet another example, the remote device
104 transmits the keep-alive signal 106 as an ultrasonic signal, a
loosely coupled magnetic induction signal, an infrared signal, or a
signal in any other medium or form suitable for use in the communication
system 100. Because the remote device is worn on the user's body, the
remote device has a range of about 1 meter. In another example, the
remote device may have a range up to about 10 meters.

[0041] The user of the implantable medical device 102 may wish to
deactivate at least a portion of the implantable medical device 102 in
certain situations, such as during an emergency or malfunction of the
implantable medical device 102. However, since at least a portion of the
implantable medical device 102 is implanted in the user's body, it is
often impractical to quickly remove the implanted component(s). In one
example, the remote device 104 provides the user with an interface for
quickly deactivating at least a portion of the functionality of the
implantable medical device 102. Interacting with the interface causes the
remote device 104 to stop transmitting the keep-alive signal 106, thereby
deactivating at least the portion of the implantable medical device 102.

[0042]FIG. 4 is a block diagram of a remote device 400. The remote device
400 is one example of the remote device 104 depicted in FIG. 1. The
remote device 400 includes a power supply 402, an interface component
404, an I/O controller 406, a data storage 408, a processor 410, a
transmitter 412, and an antenna 414. The remote device 400 also includes
additional bus work (not shown) and/or other electrical connections (not
shown) that connect the components of the remote device 400.

[0043] The power supply 402 is a battery capable of providing power to the
remote device 400. In one example, the power supply 402 is replaceable.
In another example the power supply 402 is integral to the remote device
400 and cannot be replaced. In this example, the power supply 402 is
rechargeable or is designed to provide power to the remote device 400 for
the duration of the lifespan of the remote device 400.

[0044] The interface component 404 includes an input interface, such as a
switch or a button. The input interface is prominently displayed on the
exterior of the remote device 400 and may include an identifying label,
such as "Emergency Shut-off" In one example, it may be necessary to
deactivate all or a portion of the implantable medical device during a
medical emergency or malfunction of the implantable medical device.
Furthermore, the user of the implantable medical device may be unable to
interact with the interface component 404, such as in a situation where
the user is unconscious. To facilitate deactivation of at least a portion
of the implantable medical device during an emergency, the user or an
emergency responder may operate the input interface of the interface
component 404.

[0045] Activating the input interface of the interface component 404
results in the interface component 404 sending an input signal to the I/O
controller 406. The I/O controller 406 receives the input signal from the
interface component 404 and sends a shut-off signal to the processor 410.
When the input interface of the interface component 404 is not activated,
the interface component 404 does not send the input signal to the I/O
controller 406. Likewise, the I/O controller 406 does not send the
shut-off signal to the processor 410.

[0046] The data storage 408 is any type of non-transitory, tangible,
computer readable media known or later developed configurable to store
program code for execution by the remote device 400 and/or other data
associated with the remote device 400. The data storage 408 may store a
signal identifier that is included in a transmission of the keep-alive
signal 420. In one example, the signal identifier is unique to the remote
device 400. In another example, the signal identifier is unique to the
implantable medical device. In yet another example, the data storage 408
stores multiple signal identifiers that are included in the keep-alive
signal 420. For instance, the remote device 400 may be used to transmit
the keep-alive signal 420 to multiple implantable medical devices. In
this case, the data storage 408 stores an identifier for each of the
multiple implantable medical devices.

[0047] The processor 410 determines the transmitting mode of the remote
device 400. When the remote device 400 is on, the processor 404 sends a
first signal to the transmitter 412 indicating that the transmitter 412
should transmit the keep-alive signal 420. Upon receiving the shut-off
signal from the I/O controller 406, the processor 410 sends a second
signal to the transmitter 412 indicating that the transmitter 412 should
not transmit the keep-alive signal 420. In one example, the processor 410
includes a signal identifier in the first signal. In another example, the
processor 410 includes multiple signal identifiers in the first signal,
such as in a situation where the remote device 400 transmits the
keep-alive signal 420 to multiple implantable medical devices.

[0048] The transmitter 412 is configured to transmit the keep-alive signal
420. In one example, the transmitter 412 transmits the keep-alive signal
420 in the RF spectrum, preferably in an ISM frequency band, such as a
band from about 2.4 GHz to about 2.5 GHz, though the transmitter 412 may
transmit the keep-alive signal 420 in a different ISM frequency band. In
another example, the transmitter 412 transmits the keep-alive signal 420
in the low frequency spectrum. In yet another example, the transmitter
412 transmits the keep-alive signal 420 as an infrared signal, an
ultrasonic signal, a magnetic signal, or a signal in any other form or
medium suitable for transmitting the keep-alive signal 420 to the
implantable medical device.

[0049] The transmitter 412 also receives one of the first signal and the
second signal from the processor 410. When the transmitter 412 receives
the first signal, the transmitter 412 transmits the keep-alive signal 420
in a normal transmitting mode. In one example, the transmitter 412
transmits the keep-alive signal 420 at a first transmission rate when in
the normal transmitting mode. For instance, if the transmission rate is
one transmission every 1 msec, the transmitter 412 transmits the
keep-alive signal once every 1 msec. In another example, the first
transmission rate is any rate suitable for ensuring the implantable
medical device operates in the normal operating mode. The transmitter 412
continues transmitting the keep-alive signal 420 at the first
transmission rate until the transmitter 412 receives the second signal
from the processor 410.

[0050] When the transmitter 412 receives the second signal from the
processor 410, the transmitter 412 does not transmit the keep-alive
signal 420 in the normal transmitting mode. In one example, when the
transmitter 412 receives the second signal from the processor 410, the
transmitter 412 does not transmit the keep-alive signal 420 until the
transmitter 412 receives the first signal from the processor, indicating
that input interface of the interface component 404 is no longer
activated.

[0051] Alternatively, the transmitter 412 transmits the keep-alive signal
420 in a safe transmitting mode. In one example, the safe transmitting
mode includes a cycle in which the transmitter 412 transmits the
keep-alive signal 420 during an on interval and does not transmit the
keep-alive signal during an off interval. During the on interval, the
transmitter 412 transmits the keep-alive signal at the first transmission
rate. For instance, the first transmission rate is one transmission every
1 msec, the on interval is 20 msec, and the off interval is 20 msec.
Thus, the transmitter 412 transmits the keep-alive signal 420 once every
1 msec for 20 msec and does not transmit the keep-alive signal during the
off interval. The transmitter 412 repeats the cycle until the transmitter
412 receives the first signal from the processor 410, indicating that
input interface of the interface component 404 is no longer activated.

[0052] In another example, the transmitter 412 transmits the keep-alive
signal at a second transmission rate when in the safe transmitting mode.
Transmitting at the second transmission rate results in fewer
transmissions of the keep-alive signal 420 during a time period than
transmitting at the first transmission rate during the time period. For
example, if the first transmitting rate is one transmission every 1 msec,
the second transmission rate is one transmission every 2 msec. The
transmitter 412 continues transmitting the keep-alive signal 420 at the
second transmission rate until the transmitter 412 receives the first
signal from the processor 410.

[0053] The transmitter 412 may also include a signal identifier in each
transmission of the keep-alive signal 420. In one example, the signal
identifier is stored in the data storage 408, and the processor 410
includes the signal identifier in the first signal. In another example,
the signal identifier is not stored in the data storage 408 and the first
signal does not include the signal identifier. In this example, the
transmitter 412 is configured to include the signal identifier in the
keep-alive signal 420. In yet another example, the transmitter 412
includes multiple signal identifiers in the keep-alive signal. In this
example, the transmitter 412 receives the multiple identifiers from the
processor 410 in the first signal. Alternatively, the transmitter 412 is
configured to include each of the multiple identifiers in the keep-alive
signal 420.

[0054] The antenna 414 is configured to transmit the keep-alive signal
420. In one example, the antenna 414 is configured to transmit the
keep-alive signal 420 in the RF spectrum, preferably in an ISM frequency
band, such as a band of about 2.4 GHz to about 2.5 GHz. In another
example, the antenna 414 is configured to transmit the keep-alive signal
in the low frequency spectrum. In yet another example, the transmitter
412 transmits the keep-alive signal 420 as an electro-magnetic signal. In
this example, the antenna 414 is replaced with a component suitable for
transmitting the keep-alive signal 420.

[0055]FIG. 5 is a flow diagram of a method 500. The method 500 allows a
component of an implantable medical device to determine whether the
implantable medical device received a keep-alive signal. While the
processing component 300 and the remote device 400 are used for purposes
of describing the method 500, it is understood that other devices may be
used.

[0056] The method 500 may include one or more operations, functions, or
actions as illustrated in blocks 502516. Although the blocks are
illustrated in sequential order, these blocks may be performed in
parallel and/or in a different order than those described herein. Also,
the various blocks may be combined into fewer blocks, divided into
additional blocks, and/or removed based upon the desired implementation.

[0057] In addition, for the method 500 and other processes and methods
disclosed herein, the flow diagram shows functionality and operation of
one possible implementation of one example. In this regard, each block
may represent a module, a segment, or a portion of program code, which
includes one or more instructions executable by a process for
implementing specific logical functions or steps in the process. The
program code may be stored on any type of computer readable medium, such
as a storage device including a disk or hard drive, for example. The
computer readable medium may include non-transitory computer readable
media, such as a computer readable media that stores data for a short
period of time, such as register memory, processor cache, or Random
Access Memory ("RAM"). The computer readable medium may also include
non-transitory computer readable media suitable as secondary or
persistent long term storage, such as read-only memory ("ROM"), optical
or magnetic discs, compact-disc read-only memory ("CD-ROM"), or the like.
The computer readable medium may also include any other volatile or
non-volatile storage systems. The computer readable medium may be
considered computer readable storage medium, for example, or a tangible
storage device.

[0058] In addition, for the method 500 and other processes and methods
discussed herein, each block of FIG. 5 may represent circuitry that is
wired to perform the specific logical functions of the process.

[0059] At block 502, the processing component 300 receives an
initialization signal. In one example, the initialization signal is the
keep-alive signal 320 sent from the remote device 400. In this example,
the receiver 310 receives the initialization signal via the antenna 308
and converts the initialization signal into a converted initialization
signal. The receiver 310 sends the converted initialization signal to the
control processor 314, and the control processor 314 determines whether
the signal identifier included in the converted initialization signal
matches the link identifier stored in the data storage 312. Upon
determining that the signal identifier matches the link identifier, the
control processor 314 sends a control signal to the output interface
component 316 indicating the operating mode as the normal operating mode.
In another, example the control signal indicates that the operating mode
is an operating mode other than the normal operating mode, such as the
safe operating mode.

[0060] In still another example, the processing component 300 receives the
initialization signal from an additional remote device. The receiver 310
may receive the initialization signal via the antenna 308 and may send a
converted initialization signal to the control processor 314.
Alternatively, the control processor 314 receives the converted
initialization signal from another component (not shown) of the
processing component 300. In this example, the converted initialization
signal includes the operating mode of the implantable medical device,
which the control processor 314 includes in the control signal.

[0061] At block 504, the control processor 314 commences a cycle for
receiving the keep-alive signal 320 by starting a timer. The timer
represents a period of time in which the processing component 300
receives the keep-alive signal 320. In one example, the timer is set at
about 2 msec, though in another example the period of time is as long as
about 24 hours or even longer.

[0062] At block 506, the processing component 300 receives the keep-alive
signal 320. The receiver 310 receives the keep-alive signal 320 via the
antenna 308. The receiver 310 converts the keep-alive signal 320 into the
converted keep-alive signal and sends the converted keep-alive signal to
the control processor 314.

[0063] At block 508, the control processor 314 executes instructions for
determining whether the keep-alive signal 320 was received. Included in
this determination is determining whether at least one signal identifier
in the converted keep-alive signal matches the link identifier stored in
the data storage 312. If the control processor 314 determines that at
least one signal identifier in the converted keep-alive signal matches
the link identifier, the control processor 314 determines that the
processing component 300 received the keep-alive signal 320, and the
control processor 314 determines the operating mode of the implantable
medical device at block 512.

[0064] At block 510, the control processor 314 determines if the timer has
expired upon determining that the processing component 300 did not
receive the keep-alive signal 320 at block 508. If the time has not
expired, the processing component 300 may still receive the keep-alive
signal 320 in the current cycle. Thus, the processing component 300
reattempts to receive the keep-alive signal 320 at block 506. If the
timer has expired at block 510, the control processor 314 determines the
operating mode of the implantable medical device.

[0065] At block 512, the control processor 314 determines the operating
mode of the implantable medical device. In one example, the control
processor 314 may determine the operating mode by executing instructions
capable of implementing the method 600 described with reference to FIG.
6. In another example, the control processor 314 executes any set of
instructions suitable for determining the operating mode of the
implantable medical device.

[0066]FIG. 6 is a flow diagram of a method 600. The method 600 allows a
component of an implantable medical device to determine the operating
mode of the implantable medical device. While the processing component
300 is used for purposes of describing the method 600, it is understood
that other devices may be used. The method 600 may include one or more
operations, functions, or actions as illustrated in blocks 602612.
Although the blocks are illustrated in sequential order, these blocks may
be performed in parallel and/or in a different order than those described
herein. Also, the various blocks may be combined into fewer blocks,
divided into additional blocks, and/or removed based upon the desired
implementation.

[0067] At block 602, the control processor 314 determines a number of
missed signals. The number of missed signals represents the number of
cycles--such as the cycle beginning at block 504 in the method 500--in
which the processing component 300 did not receive keep-alive signal 320
in a sample interval, where the sample interval is an integer number of
cycles. In one example, the sample interval is the last twenty cycles for
receiving the keep-alive signal 320. In another example the sample
interval is a number of cycles that may be greater than or less than
twenty. The data storage 312 may store number of missed signals and the
sample interval.

[0068] At block 604, the control processor 314 compares the number of
missed signals to a maximum number of missed signals. The maximum number
of missed signals represents the maximum allowable number of cycles in
which the processing component 300 does not receive the keep-alive signal
320 and continues to operate. In one example, the maximum number of
missed signals is fifteen, though the maximum number of missed signals
may be any integer less than or equal to the time interval. If the number
of cycles is less than the maximum number of missed signals, the control
processor 314 compares the number of missed signals to a threshold number
of missed signals, at block 606. If the number of missed signals is
greater than or equal to the maximum number of missed signals, then the
control processor 314 determines that the operating mode of the
implantable medical device is the deactivated mode, at block 610.

[0069] The number of missed signals may be greater than or equal to the
maximum number of missed signals in several circumstances. In one
example, with reference to FIG. 1, an individual may turn the remote
device 104 off. Alternatively, the user or an emergency responder
activates an emergency shut-off component of the remote device 104, such
as the interface component 404 described in FIG. 4, causing the remote
device 104 to cease transmitting the keep-alive signal 106. In either
case, the remote device 104 no longer transmits the keep-alive signal
106, preventing the implantable medical device 102 from receiving the
keep-alive signal 106.

[0070] In another example, if the implantable medical device 102 is
outside of the transmission range of the remote device 104, the
implantable medical device 102 cannot receive the keep-alive signal 106.
For example, the timer (as discussed above with respect of method 500) is
set at about 2 msec and the maximum number of missed signals is fifteen.
In this example, if the implantable medical device 102 is outside the
range of the remote device 104 for about 30 msec or longer in about a 40
msec period, the number of missed signals will generally be greater than
or equal to the maximum number of missed signals.

[0071] Comparing the number of missed signals to the maximum number of
missed signals accounts for potential errors in the implantable medical
device receiving the keep-alive signal. However, in one example, the user
may wish to deactivate the component link as soon as a keep-alive signal
is missed. In this example, the maximum number of missed signals is one,
and the control processor 314 determines that the operating mode of the
implantable medical device is the deactivated mode as soon as the
processing component 300 fails to receive the keep-alive signal 320 in a
given time interval.

[0072] Returning to FIG. 6, at block 606, the control processor 314
compares the number of missed signals to the threshold number of missed
signals. The threshold number of missed signals represents an allowable
number of cycles in which the processing component 300 does not receive
the keep-alive signal and continues to operate in a normal operating
mode. In one example, the threshold number of missed signals is five,
though in another example the threshold number of missed signals is any
integer less than maximum number of missed signals. For instance, if the
maximum number of missed cycles is fifteen, the threshold number of
missed signals can be any number less than fifteen.

[0073] If the number of missed signals is greater than the threshold
number of missed signals, then the control processor 314 determines that
the operating mode of the implantable medical device is the safe
operating mode, at block 612. Otherwise, the control processor 314
determines that operating mode of the implantable medical device is the
normal operating mode, at block 608.

[0074] In one example, the implantable medical device is not configured to
operate in the safe operating mode. In this example, the implantable
medical device does not execute block 606 of method 600, and the
implantable medical device continues operating in the normal operating
mode as long as the number of missed signals is less than the maximum
number of missed signals. In another example, the implantable medical
device continues operating regardless of the number of missed signals. In
this example, the implantable medical device does not perform block 604
of the method 600.

[0075] Returning to FIG. 5, at block 514, the control processor 314
determines whether the operating mode of the implantable medical device
is the deactivated mode. If the control processor 314 determines that the
operating mode is not the deactivated mode, the cycle recommences at
block 504. If the control processor 314 determines that the operating
mode of the implantable medical device is the deactivated mode, the
method 500 ends. When the implantable medical device operates in the
deactivated mode, conditions exist such that the processing component 300
cannot receive the keep-alive signal 320. In order to restore a
deactivated portion of the implantable medical, the implantable medical
device receives an initialization signal, thereby reinitiating the method
500.

[0076] While various aspects and embodiments have been disclosed herein,
other aspects and embodiments will be apparent to those skilled in the
art. The various aspects and embodiments disclosed herein are for
purposes of illustration and are not intended to be limiting, with the
true scope and spirit being indicated by the following claims.